The foremost objective is to develop an historically definitive study of Old Order Amish population patterns. We wish to explore the impact of progressively restrictive circumstances upon the fertility norms and behavior of the Old Order Amish, employing both survey and ethnographic methods, and--in exchange--provide information to the Amish which is of value to them. This investigation shall document certain fundamental changes in social organization experienced by the Old Order Amish within recent years. In particular we seek to learn more about the extent to which population pressures are forcing change in the modes of adaptation of this "isolate" subculture to its surrounding ecology and culture. The very high rate of population increase among the Amish has presumably intensified their competition with the surrounding culture and heightened intergroup conflict, with the consequence of a progressive loss of members and departure from the old values. To what extent have values changed? What is the rate of membership loss? What is the current rate of net population increase? Are marriages delayed more now than in the older cohorts? Is contraceptive fertility regulation employed? If so, among which subsects or in which geographical (ecologic) circumstances?